package cn.feng.thinkInJava.a9_2_泛型.generics.a15_02_02;

//: generics/LinkedStack.java
// A stack implemented with an internal linked structure.
/**一个堆栈类
 * @author fengyu
 * @date  2015年8月9日
 * @param <T>
 */
public class LinkedStack<T>
{
	private static class Node<U>
	{
		U item;
		Node<U> next;
		
		Node()
		{
			item=null;
			next=null;
		}
		
		Node(U item,Node<U> next)
		{
			this.item=item;
			this.next=next;
		}
		
		boolean end()
		{
			return item==null&&next==null;
		}
	}
	private Node<T> top=new Node<T>(); // End sentinel
	
	public void push(T item)
	{
		top=new Node<T>(item,top);
	}
	
	public T pop()
	{
		T result=top.item;
		if(!top.end())
			top=top.next;
		return result;
	}
	
	public static void main(String[] args)
	{
		LinkedStack<String> lss=new LinkedStack<String>();
		for(String s:"Phasers on stun!".split(" "))
			lss.push(s);
		String s;
		while((s=lss.pop())!=null)
			System.out.println(s);
	}
} /* Output:
stun!
on
Phasers
*///:~
